The present invention relates to a copper-lead alloy bearing and, in particular, to a copper-lead alloy bearing having an excellent corrosion resistance.
A copper-lead alloy bearing with improved corrosion resistance has been disclosed in JP-A-57-185944. This alloy is formed as a bimetal in which an alloy powder consisting of 2 to 10 wt % Ni, 8 to 27 wt % Pb, 0.5 to 10 wt % Sn, and the balance of Cu is sintered on a back metal consisting of steel. When this alloy powder is sintered on the back metal, Pb phase is prevented from being agglomerated so that the Pb phase may be fine in size and so that discrete and uniform distribution of the Pb phase may be obtained, with the results that the acid corrosion of Pb in a lubricant is said to be prevented and that the corrosion resistance of the bearing is said to be improved.
In recent years, however, it is tried to further reduce friction by use of such an engine oil as having additives of a large amount of sulfur. This makes it necessary for bearings to have an excellent corrosion resistance even in a case where a lubricant containing a large amount of sulfur is used. That is, in a lubricant with a high sulfur content, since Cu phase which is the matrix of the alloy is preferentially corroded by sulfur, conventional copper-lead alloy bearings are often insufficient in terms of corrosion resistance. In addition, some copper-lead alloy bearings, which have improved corrosion resistance to lubricants with a high sulfur content, are inferior in corrosion resistance to degraded lubricants.